JP5576186B2 - Chair - Google Patents

Description

  The present invention is a chair, particularly when not in use, the rear part of the seat is lifted, and when the seated person sits, the seat abuts against the seated person's buttocks and rotates to a substantially horizontal position together with the buttocks. Thus, the present invention relates to a chair that guides sitting and raises the rear part of the seat to assist standing when the seated person rises.

  As this type of chair, the seat is supported with respect to the lower structure of the chair as being rotatable between a use position that is inclined horizontally or rearwardly downward and a non-use position that is inclined rearwardly upward, A backrest is pivotally attached to the rear portion of the seat so that the backrest can be rotated between a standing position and a rearward tilting position, and the seat is biased toward a non-use position and the backrest is biased toward a standing position. Provided with urging means, and further provided with linking means for linking the seat and the backrest so as to maintain the backrest in a substantially vertical state while the seat rotates from the non-use position to the use position. (See, for example, Patent Document 1).

  In addition, there is one in which a seat and a backrest are moved in the same manner as described above by using a link mechanism and elastic resistance means (see, for example, Patent Document 2).

JP 2010-104562 A Japanese Patent No. 4379538

However, in any of the conventional chairs as described above, a large number of link mechanisms must be disposed below the seat, so that a large space for accommodating them must be secured below the seat. In addition, the link mechanism may be exposed to the outside, and the beauty of the chair may be impaired.
In particular, in a case where the middle part in the front-rear direction of the seat is pushed up with a link facing in the up-down direction, a large space in the up-down direction must be secured below the seat.

  The present invention has been made in view of the above problems, and includes an urging means for urging the seat upward, and a pushing rod for pushing the lower end of the backrest backward when the seat is turned downward. An object of the present invention is to provide a chair with a simple structure and good appearance that can be arranged in a narrow space in the vertical direction below the seat without interfering with each other and in a balanced manner in the horizontal direction.

According to the present invention, the above problem is solved as follows.
(1) The support base supported by the legs, and pivotally attached to the support base with a pivot axis that faces in the left-right direction, and rotates between a use position that inclines horizontally or rearwardly downward, and a non-use position that inclines rearwardly upward. A seat that is movable, a backrest that is pivotally attached to a rear portion of the seat with a shaft facing in the left-right direction, and a backrest that is rotatable between a standing position and a rearward tilt position; and provided on the support base; and An urging means for urging the rear portion of the seat upward from the pivot; and a portion of the support base that is below the pivot and a portion of the backrest that is lower than the shaft; By pushing the lower end backward, the backrest is maintained in an upright state, and by elastically contracting, the backrest can be tilted backward with respect to the seat. In the chair provided with Is fixed to the lower surface of the seat, and the other end is fixed to a portion of the support base below the pivot, and the middle portion is elastically bent in a U shape. Means, and the pushing rod is disposed between the elastic bending means.

With such a configuration, the urging means that urges the seat upward and the push rod that pushes the lower end of the backrest backward when the seat rotates downward are narrow in the vertical direction below the seat. They can be arranged in the space in a balanced manner without interfering with each other.
Furthermore, as the urging means and the push rod can be arranged in a narrow space in the vertical direction below the seat, the appearance as a chair can be improved.

(2) In the above item (1), the left and right elastic bending means are arranged so as to expand toward the rear in a plan view.

  With such a configuration, the rear portion of the seat whose front end portion is pivotally attached to the support base can be stably supported without wobbling in the left-right direction.

(3) In the above item (1) or (2), each elastic bending means is a leaf spring, one end thereof is fixed to the lower surface of the seat, and the other end together with the front end of the push rod, It is pivotally attached to the support base with a common axis facing left and right.

  With such a configuration, not only can the structure be simplified, but also the pivoting operation of each elastic bending means and the push rod to the support base can be simplified.

(4) A supporting base supported by legs, a use position in which a front portion is pivotally attached to the support base with a pivot that faces in the left-right direction, and is inclined horizontally or rearwardly downward, and an unused position that is inclined rearwardly upward A seat that can be pivoted between, a lower part pivotally attached to the rear part of the seat with a shaft facing in the left-right direction, and a backrest that can be pivoted between a standing position and a rearward tilted position, and provided on the support base An urging means for urging the rear portion of the seat upward from the pivot, and a portion of the support base that is lower than the pivot and a portion of the backrest that is lower than the shaft. By pushing the lower end of the backrest backward, the backrest is maintained in an upright state, and by elastic contraction, the backrest can be tilted backward with respect to the seat. In a chair provided with a pushing rod, the biasing means The elastic base is provided with elastic expansion / contraction means facing each of the ends connected to a portion of the support base below the pivot and a portion of the seat rearward of the pivot, and the push rod is a front end of the support base. A pair of left and right foot pieces fastened to a support base on both sides of the elastic expansion / contraction means, an elastic bending portion connected to the rear end of both foot pieces, and the two foot pieces below the elastic expansion / contraction means A connecting piece to be connected is provided.

With such a configuration, the urging means that urges the seat upward and the push rod that pushes the lower end of the backrest backward when the seat rotates downward are narrow in the vertical direction below the seat. They can be arranged in the space in a balanced manner without interfering with each other.
Furthermore, as the urging means and the push rod can be arranged in a narrow space in the vertical direction below the seat, the appearance as a chair can be improved.

(5) In the above item (4), the front end portion of the elastic expansion / contraction means and the front end portions of both feet of the push rod are pivotally attached to the support base with a common axis facing in the left-right direction.

  With such a configuration, not only can the structure be simplified, but also the pivoting operation of the elastic expansion / contraction means and the push rod to the support base can be simplified.

(6) In the above item (4) or (5), the urging means further includes one end fixed to the lower surface of the seat and the other end fixed to a portion of the support base below the pivot, It is assumed that a pair of left and right elastic bending means are formed so that the portion is substantially U-shaped and elastically bent, and an elastic expansion / contraction means and a push rod are disposed between both elastic bending means.

  With such a configuration, the urging force of the urging means can be increased without breaking the balance of the urging means in the left-right direction, and the left and right elastic bending means can be moved in the vertical direction below the seat. In a narrow space without interfering with each other and without interfering with the push rod.

(7) In the above item (6), each elastic bending means is a leaf spring, one end thereof is fixed to the lower surface of the seat, and the other end is connected to the front end of the elastic expansion / contraction means and the front end of the push rod. Along with the part, it is pivotally attached to the support base with a common axis facing in the left-right direction.

  With such a configuration, the structure of the elastic bending means can be simplified and manufactured at low cost, and the pivots of the elastic bending means, the elastic expansion / contraction means, and the push rod to the support base can be reduced. The wearing operation can be further simplified.

  According to the present invention, the urging means for urging the seat upward and the push rod for pushing the lower end portion of the backrest backward when the seat is turned downward are arranged in a narrow space in the vertical direction below the seat. In addition, it is possible to provide a chair with a simple structure and good appearance that can be disposed in a balanced manner in the left-right direction without interfering with each other.

It is a front view in the non-use state of one embodiment of the chair of the present invention. Similarly, it is a side view. Similarly, it is a side view in a use state. Similarly, it is a side view when the backrest is tilted backward in the use state. Similarly, it is a center vertical side view which shows the center part in the chair of a non-use state, abbreviate | omitting the cushion material of the seat. Similarly, it is the partial exploded perspective view which looked at the member with which the support base and the support base were mounted from diagonally forward upper part. It is a top view of a leaf | plate spring. It is a side view of a leaf | plate spring. It is a top view of a compression spring. It is a side view of a compression spring. It is the XI-XI line expanded sectional view in FIG.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.
As shown in FIGS. 1 to 4, the chair includes a leg body 3 having five leg rods 2 having a radial shape with a caster 1 at the tip. In the center of the leg 3, an extendable leg 4 having a gas spring (not shown) is erected, and the rear part of the support base 5 facing forward is fixed to the upper end of the leg 4. The support base 5, the pedestal 4 and the leg 3 may be integrated.

  As shown in FIG. 6, the support base 5 has a shallow dish shape with a triangular shape in plan view that expands forward, and is inclined forward and upward in a side view. Further, as shown in FIG. 1, the support base 5 has an upward U-shape when viewed from the front and is open to the front. Therefore, when attaching the member to the support base 5, only the side and the rear It is easy to insert a member, a tool, etc. from the front.

  The seat 6 includes a seat plate 7 made of synthetic resin and a cushion material 8 attached to the upper surface of the seat 6. The seat 6 has both front end sides on the front end of the support base 5 and pivots 9 facing left and right. As shown in FIG. 2, each pivotally attaches to a non-use position that tilts backward and upward as shown in FIG. 2 and a use position that tilts horizontally or rearward and downward as shown in FIG. It is possible to move. The rotation range is preferably about 15 degrees.

The seat 6 is constantly urged upward toward the non-use position by an urging means 12 described later.
As shown in FIG. 2, when the seat 6 is in the non-use position, the initial contact portion P that first contacts when the seated person tries to sit is positioned behind the center line O of the pedestal 4. It is.
When the seat 6 is in the use position, the initial abutment portion P matches the stable support portion that stably supports the vicinity of the seat bone portion, which is the buttocks, when the seated person sits in an appropriate sitting posture. It is preferable to define it.

When the initial abutting portion P is positioned behind the center line O of the pedestal 4 when the seat 6 is in the non-use position, the seated person sits on the seat 6 in the non-use position. At this time, when the seated person's buttocks abuts against the initial abutting portion P of the seat 6, there is no possibility that the inconvenience of the chair moving backward occurs.
In addition, after the seated person's buttocks abuts against the initial abutting portion P of the seat 6, the seat 6 rotates together with the seated person's buttocks against the biasing force of the biasing means 12 to the use position. The user's buttocks are guided to the stable support point, so that the seated person can quickly take an appropriate seating posture and the seater's load is applied to the rear of the pedestal 4, so that the seat 6 can be seated by the rear part of the seat 6. A person's buttocks can be supported stably.

  The larger the rearward upward tilt angle of the seat 6 when it is in the non-use position, the more the initial contact part P moves forward and approaches the pedestal 4 or the front thereof. As described above, the seat 6 is rearwardly upward when the initial contact portion P is located at the non-use position so that it is located behind the center line O of the pedestal 4. It is preferable to limit the inclination angle.

  On the both sides of the rear part of the seat plate 7, the front part of the extending part 10 a that faces the front side from the lower side of the backrest 10 is located behind the center line O of the pedestal 4, and is supported in the left-right direction. As shown in FIGS. 2 and 3, the backrest 10 is pivotally attached to each other with a shaft 11, and is rotated about the support shaft 11 between a standing position facing upward and a rearward tilt position as shown in FIG. It is possible to move. Note that the specific structure of the backrest 10 and the pivotally attached portion is not directly related to the present invention, and thus detailed illustration and description thereof will be omitted.

The support base 5 is provided with a biasing means 12 that biases the rear portion of the seat 6 upward.
The urging means 12 includes an elastic expansion / contraction means 13 for connecting a portion of the support base 5 below the pivot 9 and a portion of the seat 6 behind the pivot 9, and both sides of the elastic expansion / contraction means 13. The front upper end is fixed to the lower surface, the middle portion is elastically bent into a U-shape opening forward in a side view, and the front lower end is fixed at a position below the pivot 9 in the support base 5. A pair of left and right elastic bending means 14 and 14 are provided.

In this example, as shown in FIGS. 2, 5, and 6, the elastic expansion / contraction means 13 is pivotally attached to the support base 5 with a shaft 15 in the left-right direction, and the rear end is on the lower surface of the seat 6. The gas spring 17 has a locking function and is pivotally attached to a middle portion in the front-rear direction with a shaft pin 16 in the left-right direction. However, a gas spring having a lock function, a compression coil spring, an oil damper, an air damper, or the like may be used.
In the case of a gas spring having a locking function, it is preferable to provide the unlocking operation means on a part of an armrest (not shown), for example.

  In this example, each of the left and right elastic bending means 14 is, as shown in FIGS. 18a, an upper piece 18b extending rearward from the upper mounting portion 18a, an elastic bending portion 18c that curves in a substantially semicircular arc from the rear end of the upper piece 18b toward the front lower side, and an elastic bending portion 18c A pair of left and right leaf springs made of synthetic resin having a lower piece 18d extending from the lower end to the front or the front lower side, and a lower attachment portion 18e provided at the front end of the lower piece 18d and attached to the support base 5 It consists of 18 and 18. Each leaf spring 18 may be made of metal.

  The width in the left-right direction of the lower pieces 18d, 18d in the left and right leaf springs 18, 18 is gradually reduced toward the front. This is for avoiding interference with the gas spring 17 and a push rod 23 described later, and for accommodating them collectively in a narrow space below the seat 6.

  Further, as shown in FIG. 6, the left and right leaf springs 18 and 18 are preferably arranged so that both lower pieces 18 d and 18 d expand rearward in plan view. Furthermore, it is preferable that the upper pieces 18b, 18b are also arranged so as to expand toward the rear in a plan view. By doing so, the rear part of the seat 6 can be stably supported.

  Lower mounting portions 18e, 18e in the left and right leaf springs 18, 18 are pivotally attached to both side end portions of the shaft 15.

  The shaft 15 is fixed to the front upper surface of the support base 5 as follows. That is, as shown in FIGS. 5 and 6, a recess 5a facing in the left-right direction is provided on the bottom surface of the front portion of the support base 5 below the pivot 9, and a plurality of protrusions arranged in the left-right direction in the recess 5a. The upper surface of the portion 19 is provided with U-shaped concave grooves 20 that open in both the upper and left and right directions. After the shafts 15 are fitted in the respective concave grooves 20, the presser fitting 21 is disposed on the upper surface of each protrusion 19. By fixing with the screws 22, 22, the shaft 15 is fixed to the upper surface of the front end portion of the support base 5 so as not to rotate (may be rotatable).

Since the biasing means 12 includes an elastic expansion / contraction means 13 and a pair of left and right elastic bending means 14 disposed on both sides of the elastic expansion / contraction means 13, the rear portion of the seat 6 is provided with a left and right balance. The seat 6 can be lifted well and can support the seat 6 stably.
Moreover, since the elastic expansion-contraction means 13 and the elastic bending means 14 can be reduced in size and disposed compactly below the seat 6, the appearance of the chair can be improved.

  As described above, when the elastic expansion / contraction means 13 is a gas spring 17 and the elastic bending means 14 is a leaf spring 18, the structure of the elastic expansion / contraction means 13 and the elastic bending means 14 is simplified and can be manufactured at low cost. it can.

  Further, since the front end portion of the elastic expansion / contraction means 13 and the lower front end portion of the elastic bending means 14 are pivotally attached to the support base 5 with a common shaft 15 facing in the left-right direction, the structure can be simplified. In addition, the pivoting operation of the elastic expansion / contraction means 13 and the elastic bending means 14 to the support base 5 can be simplified.

The upper surface of the elastic bending portion 18c having a semicircular arc shape when viewed from the side in the leaf spring 18 as the elastic bending means 14 is in contact with the lower surface of the seat 6, and the leaf spring 18 is rotated downward when the seat 6 is rotated downward. By reducing the distance between the upper mounting portion 18a and the lower mounting portion 18e, the lower piece 18d is pushed rearward and upward, and the elastic bending portion 18c gradually moves rearward along the lower surface of the seat 6. The spring 18 is elastically deformed.
By elastically deforming the leaf spring 18 in this way, stress can be prevented from concentrating on the same location of the leaf spring 18, the durability of the leaf spring 18 can be improved, and the reaction force of the leaf spring 18 can be reduced. Can be increased.
As a result, the reaction force of the leaf spring 18 increases as the seat 6 is rotated downward.

A portion of the support base 5 below the pivot shaft 9 and a portion of the backrest 10 below the support shaft 11 are connected by an elastically extendable push rod 23 that faces in the front-rear direction.
When the seat 6 is pivoted downward from the non-use position to the use position, the lower end portion of the backrest 10 is pushed backward by the pushing rod 23 so that the backrest 10 is maintained in an upright state. As the heel 23 is elastically contracted, the backrest 10 can be inclined backward as shown in FIG.

As shown in FIGS. 6 and 9 to 11, the push rod 23 is pivotally attached to the support base 5 by the left and right shafts 15 on both sides of the gas spring 17 whose front end portion is the elastic expansion / contraction means 13. A pair of left and right leg pieces 23a, 23a that are hard and inflexible, and a pair of left and right elastic flexures 23b, 23b that are connected to the rear ends of both leg pieces 23a, 23a and face the rear of a circular cross section; A rigid and non-flexible connecting piece 23c that connects the rear ends of both foot pieces 23a and 23a below the gas spring 17 and a hard and non-flexible that connects the rear ends of both elastic flexures 23b and 23b. It is comprised by the compression spring which has the flexible connection part 23d.
The central portion of the connecting piece 23 c is recessed downward so as not to interfere with the lower surface of the gas spring 17. The push rod 23 is preferably integrally formed of, for example, a polyamide-based hard synthetic resin.

A left and right shaft hole 24 that is inserted through the shaft 15 is formed at the front end of the left and right foot pieces 23a, 23a.
The connecting portion 23d that is wide in the left-right direction at the rear end is also provided with a shaft hole 25 that faces in the left-right direction. The shaft hole 25 is connected to the connecting portion 23d in the left-right direction on the front surface of the lower end of the backrest 10. A shaft pin 27 for pivotally mounting on a pair of left and right bearing pieces 26 projecting forward at the center is inserted (see FIG. 5).

The left and right elastic flexures 23b, 23b are curved in a generally convex arc shape outward in the left-right direction of the chair, and the cross-sectional shape is substantially circular.
The left and right elastic bent portions 23b and 23b of the push rod 23, the connecting pieces 23c connecting the respective end portions, and the connecting portion 23d are formed in a closed loop shape having a substantially circular shape in plan view.

  The push rod 23 is arranged so that both elastic bending portions 23b and 23b are arranged on the left and right sides of the chair, and is connected to the support base 5 and the backrest 10 so as to be elastic when the backrest 10 is tilted backward. As shown by a two-dot chain line in FIG. 9, the bent portions 23b and 23b are elastically bent so as to swell outward in the left-right direction. The left and right elastic bent portions 23b and 23b are curved in an inwardly arcuate shape opposite to the above, and both elastic bent portions 23b are elastically bent inward in the left-right direction of the chair. Sometimes it does.

  As shown in FIG. 10, the middle part of the left and right elastic flexures 23b, 23b is slightly curved downward in a side view, and a compressive load in the front-rear direction is applied to both elastic flexures 23b. In this case, the intermediate portion can be elastically deformed in the lower direction perpendicular to the plane including both elastic flexures 23b. Note that the elastic bending portion 23b may be curved in an upward arc shape, contrary to the above.

  When the compression spring used as the push rod 23 is subjected to a longitudinal compressive force between the front and rear ends, both elastic bending portions 23b and 23b are elastically bent in a direction perpendicular to the compression direction. Even if one of the members (the support base 5 and the backrest 10) moves relative to the backrest 10 as described above, both the elastic bending portions 23b and 23b are effectively elastically bent. Thus, the spring force can be exerted, and the versatility becomes high.

In addition, since the structure is simple compared to a cylinder-type compression spring such as a gas spring, it is possible to provide an inexpensive and lightweight compression spring.
Further, the elastic bent portions 23b and 23b and the hard connecting pieces 23c and 23d before and after connecting the end portions thereof are circular or non-circular in plan view (when elastically bending inward with respect to each other). Etc.), the elastic bending portion 23b can be effectively elastically bent to obtain a large spring force, and sufficient strength and durability against repeated loads can be obtained. Can have. Moreover, since each elastic bending portion 23b has a substantially circular cross section, it can be effectively elastically deformed in any direction.

  Since both elastic flexures 23b can be elastically deformed in a direction perpendicular to the plane including them, the relative movement amount between the front and rear ends becomes large, and the backrest 10 is greatly inclined backward. Can do.

  When the compression spring as described above is mounted as the push rod 23 between the support base 5 and the backrest 10 in the chair of the above embodiment, when the backrest 10 is tilted backward, the left and right elastic flexures 23b and 23b are elastically bent in the left-right direction, so that it is not necessary to provide a vertical bending space for the push rod 23 between the support base 5 and the seat 6, and when the seat 6 is in the use position. Can be set low.

  In addition, the compression spring as the push rod 23 is simple and inexpensive compared to a back biasing means such as a gas spring or a rubber torsion spring, so that the chair can be reduced in weight, Cost reduction can be achieved.

  Further, the push rod 23 has a pair of left and right foot pieces 23a at the front portion and a connecting portion 23d having a wide width at the rear portion in the left-right direction, and a shaft 15 and a shaft pin 27 in the left-right direction, respectively. Since it is pivotally attached to the flange 10, it can be elastically deformed stably.

  The front end portions of the foot pieces 23a, 23a of the push rod 23 are connected to the front end portion of the gas spring 17 as the elastic expansion / contraction means 13 and the lower attachment portions 18e, 18e of the left and right leaf springs 18, 18 as the elastic bending means 14. In addition, since it is pivotally attached to the support base 5 with a common shaft 15 facing in the left-right direction, not only can the structure be further simplified, but also the elastic expansion / contraction means 13, the elastic bending means 14 and the push rod to the support base 5. The pivoting operation with 23 can be further simplified.

  In the non-use state shown in FIG. 2, the chair configured as described above is lifted upward by the urging force of the urging means 12, and the seat 6 is positioned at a non-use position where the seat 6 inclines rearward upward. The backrest 10 is held in an upright position substantially facing upward by the extension of the push rod 23.

  In this state, when the seated person tries to sit down, the seated person's buttocks first come into contact with the initial contact part P of the seat 6 as described above, and the seat 6 together with the seated person's buttocks is attached to the biasing means 12. It is rotated to the use position shown in FIG. 3 against the force, and the seat occupant's buttocks are guided to the stable support point, so that the seat occupant can quickly take an appropriate seating posture.

  When the seated person leans back on the backrest 10 and tilts the back backward from the sitting state shown in FIG. 3, the backrest 10 is elastically contracted by the push rod 23, and the support shaft 11 is centered. It is rotated to a rearward tilt position as shown in FIG. At the initial stage of the elastic contraction of the push rod 23, the hard connecting portion 23d is pushed forward by the shaft pin 27, and at this time, the left and right elastic bent portions 23b, 23b are slightly connected to the connecting portion 23d. While being twisted in the vertical direction, the entire elastic bending portions 23b, 23b are elastically bent so as to bulge outward in the left-right direction as shown by a two-dot chain line in FIG. 9, and slightly meander in the vertical direction. It is elastically deformed.

  When the seated person returns his / her back to the front, the backrest 10 is rotated forward about the support shaft 11 by the extension by the elastic restoring force of the push rod 23 and returned to the original standing position.

  When the seated person tries to stand up from the seating state shown in FIG. 3, the seat 6 is attached so as to rotate upward toward the non-use position by the synergistic action of the elastic expansion / contraction means 13 and the elastic bending means 14. The seated person can be assisted in standing up.

  The present invention is not limited to the above-described embodiment, and can be implemented in various modified forms without departing from the scope of the claims.

DESCRIPTION OF SYMBOLS 1 Caster 2 Leg rod 3 Leg 4 Leg column 5 Support base 5a Recess 6 Seat 7 Seat plate 8 Cushion material 9 Axis 10 Backrest 10a Extension part 11 Support shaft 12 Energizing means 13 Elastic expansion / contraction means 14 Elastic bending means 15 Shaft 16 shaft pin 17 gas spring 18 leaf spring 18a upper mounting portion 18b upper piece 18c elastic bending portion 18d lower piece 18e lower mounting portion 19 convex portion 20 concave groove 21 presser fitting 22 screw 23 push rod (compression spring)
23a foot piece (hard part)
23b elastic bending part 23c connection piece (hard part)
23d connecting part (hard part)
24, 25 Shaft hole 26 Bearing piece 27 Shaft pin

Claims (7)

A base supported by legs,
A seat pivotally attached to the support base with a pivot that faces in the left-right direction, and is rotatable between a use position that is inclined horizontally or rearward and a non-use position that is inclined rearward and upward,
On the back of the seat, the lower part is pivotally attached with an axis that faces in the left-right direction, and the backrest that can be rotated between the standing position and the rearward tilting position;
A biasing means provided on the support base and biasing a rear part upward from the pivot in the seat;
A portion of the support base below the pivot is connected to a portion of the backrest below the shaft, and the lower end of the backrest is pushed rearward when the seat is turned downward to bring the backrest into an upright state. In a chair provided with an elastically stretchable push rod that faces in the front-rear direction, which maintains and elastically contracts to allow the back to tilt backward with respect to the seat,
The biasing means has one end fixed to the lower surface of the seat and the other end fixed to a portion of the support base below the pivot so that the middle portion is elastically bent in a U-shape. A chair comprising a pair of left and right elastic bending means, wherein the push rod is disposed between both elastic bending means.   The chair according to claim 1, wherein the left and right elastic bending means are arranged so as to expand rearward in a plan view.   Each elastic bending means is a leaf spring, one end of which is fixed to the lower surface of the seat, and the other end together with the front end of the push rod is pivotally attached to the support base with a common axis facing left and right. The chair according to claim 1 or 2. A base supported by legs,
A seat that is pivotally attached to the support base with a pivot that faces in the left-right direction, and that can be rotated between a use position that is horizontally or rearwardly inclined, and a non-use position that is inclined rearwardly upward,
On the back of the seat, the lower part is pivotally attached with an axis that faces in the left-right direction, and the backrest that can be rotated between the standing position and the rearward tilting position;
A biasing means provided on the support base and biasing a rear part upward from the pivot in the seat;
A portion of the support base below the pivot is connected to a portion of the backrest below the shaft, and the lower end of the backrest is pushed rearward when the seat is turned downward to bring the backrest into an upright state. In a chair provided with an elastically stretchable push rod that faces in the front-rear direction, which maintains and elastically contracts to allow the back to tilt backward with respect to the seat,
The biasing means includes elastic expansion and contraction means facing in the front-rear direction in which each end is connected to a portion below the pivot in the support base and a portion behind the pivot in the seat, and a push rod A pair of left and right foot pieces whose front end portions are fixed to a support base on both sides of the elastic expansion / contraction means, an elastic bending portion connected to the rear ends of both foot pieces, and below the elastic expansion / contraction means A chair comprising a connecting piece for connecting the two foot pieces together.   The chair according to claim 4, wherein the front end portion of the elastic expansion / contraction means and the front end portions of both feet of the push rod are pivotally attached to a support base with a common axis facing in the left-right direction.   The urging means further has one end fixed to the lower surface of the seat and the other end fixed to a portion of the support base below the pivot, so that the middle portion is elastically bent substantially in a U shape. 6. The chair according to claim 4 or 5, wherein a pair of left and right elastic bending means is provided, and an elastic expansion / contraction means and a push rod are disposed between the elastic bending means.   Each elastic bending means is a leaf spring, one end of which is fixed to the lower surface of the seat, and the other end together with the front end part of the elastic expansion / contraction means and the front end part of the push rod is a common shaft facing in the left-right direction. The chair according to claim 6 pivotally attached to the support base.

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